You should read
Capital in the Twenty First Century.
Fuck, ya'll should be reading it.
Edit: not to sound mysterious and shit, the book claim, very persuasively, that there is no inequality equilibrium (of at the very least that it's at a super high levels) and that the very system creates very strong divergent forces that unless counteracted by strong government action (or another World War) would lead pretty terrible results.
And for real, go read it, it's one of the most important books written in recent years, and while it deals with pretty technical stuff, it does it in a very approachable and readable way.